Ethylene dichloride (1,2-dichloroethane) may be produced by the oxychlorination of ethylene wherein ethylene, a chlorine source, and an oxygen source are contacted in the vapor phase in the presence of a catalyst. Typically, a gaseous mixture of ethylene, hydrogen chloride, and oxygen are reacted in the presence of a copper halide catalyst to produce a gaseous stream of ethylene dichloride. When ethylene is so oxychlorinated, satisfactorily high yields of ethylene dichloride may be obtained under moderate reaction conditions, however, the product typically contains objectionable amounts of chloral, i.e., in excess of about 0.2 percent by weight. Chloral, in addition to being classified as a pollutant, boils quite close to ethylene dichloride and is both difficult and costly to remove by, for example, distillation, to produce high purity ethylene dichloride.
One means of purifying chloral contaminated ethylene dichloride is disclosed in U.S. Pat. No. 3,378,597 wherein the oxychlorination product gas stream is condensed to form organic and inorganic liquid phases. The organic phase containing ethylene dichloride and chloral is separated from the inorganic phase and treated with aqueous sodium hydroxide to decompose the chloral to chloroform and sodium formate. However, both chloroform and sodium formate also pose a waste disposal problem and require additional treatment, e.g., bioxidation, before being discharged to a receiving stream.